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You will find listings of the source code used to create these melodies later in this module.

Play or file the melody

The code in Listing 4 uses the standard procedure to either play or file the melody that was created in Listing 3 .

Listing 4 . Play or file the melody.
new AudioPlayOrFile01(audioParams,melody,this.args[0]).playOrFileData();}//end constructor //-------------------------------------------------------------------------//}//end class MusicComposer08.java

An extremely important concept

While this may seem like a rather innocuous result, runtime polymorphism is an extremely important concept in object-oriented programming. One of theimportant applications of runtime polymorphism is the Java Collections Framework . A series of accessible modules that explain the framework begins with Java4010 : Getting Started with Java Collections .

Run the program

I encourage you to copy the code from Listing 5 through Listing 16 . Compile the code and execute it. Experiment with the code,making changes, and observing the results of your changes. Make certain that you can explain why your changes behave as they do.


This section contains a variety of miscellaneous information.

Housekeeping material
  • Module name: Jbs2050-Runtime Polymorphism with Java Sound
  • File: Jbs2050.htm
  • Published: 08/27/14
  • Revised: 09/29/15

Financial : Although the OpenStax CNX site makes it possible for you to download a PDF file for the collection thatcontains this module at no charge, and also makes it possible for you to purchase a pre-printed version of the PDF file, youshould be aware that some of the HTML elements in this module may not translate well into PDF.

You also need to know that Prof. Baldwin receives no financial compensation from OpenStax CNX even if you purchase the PDF version of the collection.

In the past, unknown individuals have copied Prof. Baldwin's modules from cnx.org, converted them to Kindle books, and placedthem for sale on Amazon.com showing Prof. Baldwin as the author. Prof. Baldwin neither receives compensation for those sales nordoes he know who does receive compensation. If you purchase such a book, please be aware that it is a copy of a collection thatis freely available on OpenStax CNX and that it was made and published without the prior knowledge of Prof.Baldwin.

Affiliation : Prof. Baldwin is a professor of Computer Information Technology at Austin Community College inAustin, TX.

Complete program listings

Complete listing of the twelve classes required by the program discussed in this module are provided below.

Listing 5 . The class named AudioGraphSinusoidal.
/*File AudioGraphSinusoidal.java Copyright 2014, R.G.BaldwinRevised 08/23/14 This class can be used to create an 8-second melody consisting of 32 pulsesat different frequencies. ******************************************************************************/import java.io.*; import java.nio.*;import java.util.*; public class AudioGraphSinusoidal extends AudioSignalGenerator02{public AudioGraphSinusoidal(AudioFormatParameters01 audioParams,String[] args,byte[] melody){super(audioParams,args,melody); }//end constructor//-------------------------------------------------------------------------////This method returns a melody array that will play an 8-second melody // consisting of 32 pulses at different frequencies. The frequencies of the// pulses are centered on middle-C (261.63 Hz).//The frequency deviation from middle-C versus time is based on a sinusoidal // function with a frequency of 0.5 Hz. Each pulse represents one point on// a graph of the sinusoid. Pulses with frequencies at or above middle-C are // delivered to the left speaker. Pulses with frequencies below middle-C are// delivered to the right speaker. //The audio output can be thought of as an audio representation of a graph// of a sinusoid. Pulses with frequencies above middle-C represent points // on the positive lobe of the sinusoid. Increasing pitch represents// increasing amplitude on the graph of the sinusoid. Pulses with // frequencies below middle-C can be thought of as representing points on// the negative lobe of the sinusoid. In this case, decreasing pitch // represents points on the sinusoid that are further from the horizontal// axis in the negative direction. Pulses with a frequency of middle-C can // be thought of as representing points on the horizontal axis with a value// of zero. //In order to eliminate pops and clicks caused by abrupt frequency changes// in the audio signal, the amplitude of each pulse is scaled by a // triangular (rooftop) function that has a value that is zero at both ends// and 1.0 in the center with a linear progression from the center to the // ends in both directions.//Four complete cycles of the 0.5 Hz sinusoid are represented by the 32 // pulses in the 8-second melody.byte[]getMelody(){ //Set channels to 2 for stereo overriding the default value of 1.audioParams.channels = 2; System.out.println("audioParams.channels = " + audioParams.channels);//Each channel requires two 8-bit bytes per 16-bit sample. int bytesPerSampPerChan = 2;//Override the default sampleRate of 16000.0F. Allowable sample rates// are 8000,11025,16000,22050, and 44100 samples per second. audioParams.sampleRate = 8000.0F;// Specify the length of the melody in seconds.double lengthInSeconds = 8.0;//Set the center frequency. Audio pulses will be generated above and // below this frequency to represent points on the graph of a// sinusoidal function. double centerFreq = 261.63;//middle C//Create an output array of sufficient size to contain the melody at // "sampleRate" samples per second, "bytesPerSampPerChan" bytes per// sample per channel and "channels" channels. melody = new byte[(int)(lengthInSeconds*audioParams.sampleRate*bytesPerSampPerChan*audioParams.channels)];System.out.println("melody.length = " + melody.length);//Declare variables used to control the output volume on the left and // right speaker channels. These values will be used to cause pulses// representing negative values of the sinusoidal function to emit from // one speaker and pulses representing positive values to emit from// the other speaker. double gain = 0.0;double leftGain = 0.0; double rightGain = 0.0;//Declare a variable that is used to control the frequency of each pulse. double freq = 0.0;//Prepare a ByteBuffer for use byteBuffer = ByteBuffer.wrap(melody);//Compute the number of audio samples in the melody. int sampLength = (int)(lengthInSeconds*audioParams.sampleRate);//Set the length of each pulse in seconds and in samples. double pulseLengthInSec = 0.25;//in secondsint pulseLengthInSamples = (int)(pulseLengthInSec*audioParams.sampleRate); //Compute the audio sample values and deposit them in the output melody// array. for(int cnt = 0; cnt<sampLength; cnt++){ //Compute the time in seconds for this sample.double time = cnt/audioParams.sampleRate;if(cnt%pulseLengthInSamples == 0){ //Time to create a new pulse at a different pitch. Compute the// frequency for the next pulse to represent a point on a sinusoidal // function of time. This section of code could easily be modified// to create audio graphs of many different functions.//Evaluate and scale the function double val = 0.35 * Math.sin(2*Math.PI*0.5*time);//Compute the frequency for the next pulse as a deviation from the// center frequency. For this scaled sinusoidal function, the Range // is from 0.65*centerFreq to 1.35*centerFreq or from 170.05 Hz// to 353.2 Hz. freq = (1+val)*centerFreq;}//end if //Deposit audio data in the melody for each channel. Scale the amplitude// of each pulse with a triangular scale factor (rooftop shape) to // minimize the undesirable pops and clicks that occur when there is an// abrupt change in the frequency from one pulse to the next. The // following gain factor ranges from 0.0 at the ends to 1.0 in the// center of the pulse. gain = (cnt%pulseLengthInSamples)/(double)pulseLengthInSamples;if(gain>0.5){ //Change to a negative slope.gain = (pulseLengthInSamples - cnt%pulseLengthInSamples)/(double)pulseLengthInSamples;}//end if//Set the final gain to a value that is compatible with 16-bit audio // data.gain = 8000*gain; //Switch the left and right channels on and off depending on the location// of the pulse frequency relative to the center frequency. if(freq>= centerFreq){ leftGain = gain;rightGain = 0;//switch off the right channel }else{rightGain = gain; leftGain = 0;//switch off the left channel}////Compute scaled pulse values and deposit them into the melody. byteBuffer.putShort((short)(leftGain*Math.sin(2*Math.PI*freq*time)));byteBuffer.putShort((short)(rightGain*Math.sin(2*Math.PI*freq*time))); }//end for loopreturn melody;}//end method getMelody //-------------------------------------------------------------------------//}//end class AudioGraphSinusoidal //===========================================================================//

Questions & Answers

are nano particles real
Missy Reply
Hello, if I study Physics teacher in bachelor, can I study Nanotechnology in master?
Lale Reply
no can't
where we get a research paper on Nano chemistry....?
Maira Reply
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
Application of nanotechnology in medicine
has a lot of application modern world
what is variations in raman spectra for nanomaterials
Jyoti Reply
ya I also want to know the raman spectra
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
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I think
Nasa has use it in the 60's, copper as water purification in the moon travel.
nanocopper obvius
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
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Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
what is differents between GO and RGO?
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
analytical skills graphene is prepared to kill any type viruses .
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
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